As opposed to pharmacokinetics, pharmacodynamics is what a drug does to the body. When a drug is administered, it acts on the target cell populations by means of certain receptors. There are various types of receptors, and the drug-receptor complexes can produce a specific or a variety of pharmacological effects, based on the mechanisms activated. These effects can be desirable (therapeutic) or toxic/lethal and are often dose dependent. Thus, it is crucial to learn the pharmacodynamics of the drug to arrive at not only an effective, but also a safe dose, to the individual.

00:01
Let's talk about something called up and downregulations.
This is a process where the number of receptors isdependant upon receptor binding. So at the top of our image
here, you can see that upregulation refers toa system where you have more and more receptors being expressed
at the cell surface because there is very little activity.
00:23
So, the net result is, is that if you have low concentration
of a drug, your cell becomes more sensitiveto that drug because it has more receptors.
00:33
Downregulation or tachyphylaxis is where you have the
opposite. You have fewer and fewer receptorsbecause they are always being used up and broken down.
That's called downregulation and the effect on the drug istachyphylaxis, which is a reduced drug effect over time.

About the Lecture

The lecture Upregulation and Downregulation – Pharmacodynamics by Pravin Shukle, MD is from the course Pharmacokinetics and Pharmacodynamics.

Included Quiz Questions

What is the pharmacological phenomena that may be used to explain the development of drug tolerance?

Tachyphylaxis

Upregulation of receptors

Increased efficacy of the drug over time

Decreased potency of the drug

Increased drug receptor density

Author of lecture Upregulation and Downregulation – Pharmacodynamics

Pravin Shukle, MD

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